A chipping sparrow, shown tugging on some loose threads of weathered clothing while gathering nest-building materials, will emit a dry trill during much of the day, but at dawn will sing short, staccato bursts of song at each other. Robert F. Bukaty/Associated Press

The music of birds is in the air. Now that the nesting season is here, the sound of bird song is at its peak. The avian symphony begins before 4 a.m. now, much to the consternation of erstwhile sleepers who don’t appreciate such an early wake-up call.

We’ll start by contrasting two types of bird vocalizations, calls and songs. Calls are short vocalizations that serve various year-round functions. Flight calls, alarm calls and contact calls are good examples. Songs are complex vocalizations only used during the breeding season. However, the distinction between the two types of vocalizations isn’t always clear.

A male American robin changes its tune throughout the day. Carlos Osorio/Associated Press

The virtuosos of bird song are found within the group of birds called, appropriately, the songbirds, which are nested within the order of birds called the perching birds, the Passeriformes. The songbirds are joined within the perching bird order by flycatchers and other tropical families in a group called the suboscines, translated as “below songbirds”.

But wait a minute, eastern phoebes, eastern wood-pewees and olive-sided flycatchers are all suboscines, yet they are singing their hearts out? And hummingbirds, cuckoos, sandpipers and grebes emit melodious vocalizations during the nesting season. Their vocalizations are referred to as songs.  What’s a song in the bird world?

Within the songbirds, the song sung by a male has to be learned from its father or other males of the same species. The “fee-bee” song of an eastern phoebe serves as a song, but the ability to sing the song is passed on genetically. No tutoring is required. The same is true of many other species in other orders.

Bird song has two important functions. First, song is used to court females as a possible mate. Second, song is used to warn other males to keep out of a male’s territory to prevent his mate from cheating on him.

In most singing birds, a song carries dual meanings. The same sound is interpreted as a welcome by females and a deterrent by other males. Some species have different songs for the two functions. For instance, the black-throated green warbler gives an accented ending song – expressed as “zee-zee-zee-zoo-zee” where the last zee note is higher-pitched and seemingly louder – as well as an unaccented ending song – “zee-zee-zoo-zoo-zee,” in which the final zee note has the same pitch and duration as the earlier zee notes.

The accented ending song is more often given early in the breeding season and is used to attract females. Once a male has mated, it ceases giving the accented song and cranks out the unaccented song, an aggressive signal to other males.

A similar pattern occurs in the chestnut-sided warbler. The accented ending song is very distinctive (“pleased-pleased-to-meet-CHA”). But the unaccented ending song often confuses birders.

Some birds change their songs over the course of a day. If you are an early riser, listen for the song of the eastern phoebe. The familiar “fee-bee” song we hear later in the day has a third syllable at dawn (“fee-bu-bee”).

The rollicking song of an American robin is a series of two- and three-note phrases. But at dawn, a male robin throws in a new phrase, “sissely”.

Chipping sparrows give a dry trill during much of the day, usually singing from a perch 10 to 20 feet high. However, at dawn neighboring chipping sparrows fly down to the ground in a restricted area and commence to sing short, staccato bursts of song at each other. Amazing!

If you don’t get up with the songbirds, you can enjoy an unusual song given by ovenbirds. These warblers normally sing a crescendo of two-noted phrases (teacher-teacher-TEACHER). But at dusk, a different tune is sung, most often in flight above the forest. It starts as “whink-whink-ple-bleep” notes followed by a jumble of other notes.

A great free bird app is available from the National Audubon Society (audubon.org/app).  There are multiple vocalizations for every species. It’s a marvelous learning tool.

Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes reader comments and questions at whwilson@colby.edu